input[type="radio"]{
    -webkit-appearance:none;
    width: 50px;
    height: 50px;
    background-color: red;

}
div{
    width: 500px;
    height: 500px;
    border: solid;
    background-color: yellow;
}
input:checked{
    border-radius: 50%;
}
input:checked ~div{
    background-color: blue;
}